Colon or bowel cleansing is important before numerous surgical or diagnostic procedures, including colonoscopy, barium enema examination, sigmoidoscopy and colon surgery. Such procedures are often carried out on an outpatient basis and thus it is desirable that the colon cleansing be carried out by the patient at home, prior to arrival at the hospital or surgery where the procedure is to take place. It is therefore important that patient compliance is good without medical supervision if satisfactory colon cleansing is to be achieved prior to the procedure.
Intestinal lavage, in which a large volume of an aqueous electrolyte solution containing sodium sulphate and polyethylene glycol is ingested, is one of the most common methods for colon cleansing. These osmotically active agents are non-absorbable or only poorly absorbable and thus retain water in the bowel, resulting in copious diarrhea and cleansing of the colon.
For effective cleansing, many of these compositions must be ingested in quantities of between 2 to 4 liters. The unpleasant taste of these compositions combined with the large volumes required to be ingested often contributes to nausea or vomiting, resulting in poor patient compliance and failure to consume the full volume of solution. Poor patient compliance can lead to inadequate preparation of the colon which can, in turn, lead to cancellation or repetition of the colonoscopy becoming necessary or, worse, non-detection of lesions or polyps indicative of cancer risk.
A number of improved colon cleansing compositions are described in WO 2004/037292. A colon cleansing composition according to WO 2004/037292 that comprises polyethylene glycol 3350, sodium sulphate, an ascorbate component, electrolytes, sweetener and flavouring is commercialised as a powder for oral solution under the tradename MOVIPREP® (registered trademark of Velinor AG, a member of the Norgine group of companies). The MOVIPREP solution is effective despite being taken in a substantially lower volume than other colon cleansing solutions. Typically, only 2 liters of the solution need to be taken by an adult patient (along with additional clear fluid), a significant benefit when compared to taking 4 liters of previous solutions.
A recent advance in colon cleansing agents is provided by the product marketed as SUPREP by Braintree Laboratories, Inc. SUPRPEP contains 17.5 g sodium sulphate, 3.13 g potassium sulphate and 1.6 g magnesium sulphate and it is taken in a volume of 16 US fluid ounces (473 ml). A treatment comprises two doses of that solution.
Various regimens for the timing of ingestion of colon cleansing solutions are mentioned in the literature and in patient information leaflets that accompany colon cleansing products. For example, the MOVIPREP solution mentioned above may be taken (optionally with additional clear liquids also being taken) in the evening before the examination or procedure, or the MOVIPREP solution may be taken in a “split-dose” regimen, with approximately half of the cleansing solution being taken the evening before the examination or procedure (“first dose”), and the remainder being taken the following morning (“second dose”). Similarly, the SUPREP product mentioned above is recommended to be taken as first dose in the evening before the examination procedure, accompanied by an additional quart of water (946 ml), followed by a second dose in the morning of the procedure.
An alternative to the lavage solutions described above is provided by low volume hypertonic salt solutions. Examples include Fleet's phosphosoda product and sodium picosulphate solutions. These are very concentrated salt solutions and patients need ingest only a small volume of them (around 100 ml). However, these products have been associated with a hypo-osmolar state and electrolyte imbalance in subjects, particularly hyponatremia. They are particularly counter-indicated in subjects with kidney problems.
Despite the advances that have been made, all lavage-type colon cleansing products on the market continue to require a subject to ingest a large volume of solution (2 liters in the case of the MOVIPREP solution). Many subjects find the ingestion of a large volume unpleasant or difficult and poor patient compliance thus remains a problem. There remains a need for alternative colon cleansing solutions that are effective when ingested in small volumes, but do not cause electrolyte imbalances in subjects. There also remains a need for colon cleansing solutions that are more pleasant to subjects to ingest, whilst retaining good cleansing effectiveness.